775,751 research outputs found
On some invariants in numerical semigroups and estimations of the order bound
We study suitable parameters and relations in a numerical semigroup S. When S
is the Weierstrass semigroup at a rational point P of a projective curve C, we
evaluate the Feng-Rao order bound of the associated family of Goppa codes.
Further we conjecture that the order bound is always greater than a fixed value
easily deduced from the parameters of the semigroup: we also prove this
inequality in several cases
Exact dimensionality and projections of random self-similar measures and sets
We study the geometric properties of random multiplicative cascade measures
defined on self-similar sets. We show that such measures and their projections
and sections are almost surely exact-dimensional, generalizing Feng and Hu's
result \cite{FeHu09} for self-similar measures. This, together with a compact
group extension argument, enables us to generalize Hochman and Shmerkin's
theorems on projections of deterministic self-similar measures \cite{HoSh12} to
these random measures without requiring any separation conditions on the
underlying sets. We give applications to self-similar sets and fractal
percolation, including new results on projections, -images and distance
sets.Comment: 25 page
Neutron-Diffraction Measurements of an Antiferromagnetic Semiconducting Phase in the Vicinity of the High-Temperature Superconducting State of KFeSe
The recently discovered K-Fe-Se high temperature superconductor has caused
heated debate regarding the nature of its parent compound. Transport,
angle-resolved photoemission spectroscopy, and STM measurements have suggested
that its parent compound could be insulating, semiconducting or even metallic
[M. H. Fang, H.-D. Wang, C.-H. Dong, Z.-J. Li, C.-M. Feng, J. Chen, and H. Q.
Yuan, Europhys. Lett. 94, 27009 (2011); F. Chen et al. Phys. Rev. X 1, 021020
(2011); and W. Li et al.,Phys. Rev. Lett. 109, 057003 (2012)]. Because the
magnetic ground states associated with these different phases have not yet been
identified and the relationship between magnetism and superconductivity is not
fully understood, the real parent compound of this system remains elusive.
Here, we report neutron-diffraction experiments that reveal a semiconducting
antiferromagnetic (AFM) phase with rhombus iron vacancy order. The magnetic
order of the semiconducting phase is the same as the stripe AFM order of the
iron pnictide parent compounds. Moreover, while the root5*root5 block AFM phase
coexists with superconductivity, the stripe AFM order is suppressed by it. This
leads us to conjecture that the new semiconducting magnetic ordered phase is
the true parent phase of this superconductor.Comment: 1 table, 4 figures,5 page
Probiotic<i> Bacillus subtilis</i> protects against α-synuclein aggregation in <i>C. elegans</i>
How the gut microbiome affects Parkinson's disease remains unclear. Goya et al. show that the probiotic B. subtilis strain PXN21 inhibits and clears α-synuclein aggregation in a C. elegans model. The bacterium acts via metabolites and biofilm formation to activate protective pathways in the host, including DAF-16/FOXO and sphingolipid metabolism.Fil: Goya, MarÃa Eugenia. University of Edinburgh; Reino UnidoFil: Xue, Feng. University of Edinburgh; Reino UnidoFil: Sampedro Torres Quevedo, Cristina. University of Edinburgh; Reino UnidoFil: Arnaouteli, Sofia. University Of Dundee; Reino UnidoFil: Riquelme Dominguez, Lourdes. University of Edinburgh; Reino UnidoFil: Romanowski, Andrés. University of Edinburgh; Reino Unido. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones BioquÃmicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones BioquÃmicas de Buenos Aires; ArgentinaFil: Brydon, Jack. University of Edinburgh; Reino UnidoFil: Ball, Kathryn L.. University of Edinburgh; Reino UnidoFil: Stanley-Wall, Nicola R.. University Of Dundee; Reino UnidoFil: Doitsidou, Maria. University of Edinburgh; Reino Unid
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